Divermikey
Contributor
Can someone tell me the sizes of the orings for the RMS battery box and the breathing loop connection to the case? Thanks in advance.
Revo oring sizes
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MrJerez
Registered
Hi Divermikey
I tried to measure the o rings but it‘s very difficult to do it accurately given the large diameter / thin cross-section ratio.
I strongly recommend not to use any measured values but to contact REvo eg. pieter@revo-rebreathers.com
I tried to measure the o rings but it‘s very difficult to do it accurately given the large diameter / thin cross-section ratio.
I strongly recommend not to use any measured values but to contact REvo eg. pieter@revo-rebreathers.com
Here's how to measure orings larger than about 18mm with sufficient accuracy:
Take a piece of paper and cut it so that it's about 8cm wide. Roll it into a cylinder that is close to the internal diameter of your o-ring. If you have a tight roll, trim the length of the paper so there's just a modest overlap of the ends (2-10 cm, depending upon how big your o-ring is).
Put the roll inside the o-ring, and grasp the paper at the overlap point on each side near the o-ring.
Slide the edges of the paper until the roll is tight inside the o-ring. Inspect how the o-ring lies on the roll to make sure that it is at right angles to the roll, and not cocked in any way.
By the way, if your o-ring is larger than about 85mm, you may need to tape TWO pieces of paper securely together before you cut your 8cm strip.
One your have stretched your roll so that it is firmly and symmetrically inside the o-ring, hold the roll pinched at the point where the end of the paper overlaps itself with one hand. With the other, take a felt tip pen and swipe a light mark across the overlap, very close to the o-ring.
Now release the pinch and remove the roll from inside the oring. Flatten the piece of paper on the table, and carefully measure the distance between the square ends of your felt tip mark.
That distance is the inner circumference of your oring. Divide that distance by 3.14159 using the formula Circumference = Pi x Diameter.
The result is the inner diameter, or ID of your oring.
Using a micrometer, lightly grasp the edge of the o-ring by laying it flat across the jaws. That distance is the cross section of your o-ring.
With o-ring C/S and ID, the last thing you'll need is an estimate of Durometer. That comes with experience, but generally falls into one of four rough bunches.
50 Shore A - really soft orings (usually small) used on some poppets
70-75 Shore A - the most widely used hardness, and common to all low pressure hose orings
85‐90 Shore A - firm orings like the ones on some high pressure seals (some SPG hoses, piston shaft orings in piston regs)
55B Shore B - hard polyethylene orings as are found in some yoke tank valves.
Once you pick a material (Nitrile, EPDM, Silicone or Viton) you are good to go and can order at mcmaster.com
I have used this technique to purchase spare orings for my JJ-CCR instead of waiting for mail from Europe.
Take a piece of paper and cut it so that it's about 8cm wide. Roll it into a cylinder that is close to the internal diameter of your o-ring. If you have a tight roll, trim the length of the paper so there's just a modest overlap of the ends (2-10 cm, depending upon how big your o-ring is).
Put the roll inside the o-ring, and grasp the paper at the overlap point on each side near the o-ring.
Slide the edges of the paper until the roll is tight inside the o-ring. Inspect how the o-ring lies on the roll to make sure that it is at right angles to the roll, and not cocked in any way.
By the way, if your o-ring is larger than about 85mm, you may need to tape TWO pieces of paper securely together before you cut your 8cm strip.
One your have stretched your roll so that it is firmly and symmetrically inside the o-ring, hold the roll pinched at the point where the end of the paper overlaps itself with one hand. With the other, take a felt tip pen and swipe a light mark across the overlap, very close to the o-ring.
Now release the pinch and remove the roll from inside the oring. Flatten the piece of paper on the table, and carefully measure the distance between the square ends of your felt tip mark.
That distance is the inner circumference of your oring. Divide that distance by 3.14159 using the formula Circumference = Pi x Diameter.
The result is the inner diameter, or ID of your oring.
Using a micrometer, lightly grasp the edge of the o-ring by laying it flat across the jaws. That distance is the cross section of your o-ring.
With o-ring C/S and ID, the last thing you'll need is an estimate of Durometer. That comes with experience, but generally falls into one of four rough bunches.
50 Shore A - really soft orings (usually small) used on some poppets
70-75 Shore A - the most widely used hardness, and common to all low pressure hose orings
85‐90 Shore A - firm orings like the ones on some high pressure seals (some SPG hoses, piston shaft orings in piston regs)
55B Shore B - hard polyethylene orings as are found in some yoke tank valves.
Once you pick a material (Nitrile, EPDM, Silicone or Viton) you are good to go and can order at mcmaster.com
I have used this technique to purchase spare orings for my JJ-CCR instead of waiting for mail from Europe.
BIG o-rings!
Here is a tool for smaller O-rings that is pretty affordable:
MISURALL Ring Mandrel Sizer Gauge Tool US Size 2-15 EUR Size 41-76&Ring Sizer Set Size 1-13 with Half Size Ring Gauge Ring Size Measuring Tool 27 Pieces
The Parker O-Ring Sizing Cone is a decent commercial tool for larger O-rings, but isn't cheap and takes storage space.
MISURALL Ring Mandrel Sizer Gauge Tool US Size 2-15 EUR Size 41-76&Ring Sizer Set Size 1-13 with Half Size Ring Gauge Ring Size Measuring Tool 27 Pieces
The Parker O-Ring Sizing Cone is a decent commercial tool for larger O-rings, but isn't cheap and takes storage space.
KevinNM
Contributor
Most towns have an industrial o-ring supplier who can measure your o-ring accurately at the counter and probably have ones you can immediately check.
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